I manged to get my 800mhz ibook g3 working again by wedging 3 2p coins between the graphics chip and the case it has been working for almost a week now with no major problems even played the entire Return to Castle Wolfenstein on it! (@1024x786)

Sorry if I sound like a pessimist here, but I'm doubting you're going to see another year out of the thing, if you see a few months out of it. Consumer heat guns do NOT reflow solder like everyone believes they do. The only real way to fix the chip is to have someone properly reflow it using a BGA station. I'm not sure what the heat gun does, but I'm guessing it expands things just enough so that proper contact is made.